--- title: Go-Expvar description: Collect expvar-instrumented metrics and memory stats from your Go service. breadcrumbs: Docs > Integrations > Go-Expvar --- # Go-Expvar Supported OS Integration version5.4.0 ## Overview{% #overview %} Track the memory usage of your Go services and collect metrics instrumented from Go's expvar package. If you prefer to instrument your Go code using only [dogstats-go](https://github.com/DataDog/datadog-go), you can still use this integration to collect memory-related metrics. **Minimum Agent version:** 6.0.0 ## Setup{% #setup %} ### Installation{% #installation %} The Go Expvar check is packaged with the Agent, so [install the Agent](https://app.datadoghq.com/account/settings/agent/latest) anywhere you run Go services to collect metrics. ### Configuration{% #configuration %} #### Prepare the service{% #prepare-the-service %} If your Go service doesn't use the [expvar package](https://golang.org/pkg/expvar) already, import it (`import "expvar"`). If you don't want to instrument your own metrics with expvar - that is you only want to collect your service's memory metrics - import the package using the blank identifier (`import _ "expvar"`). If your service doesn't already listen for HTTP requests (with the http package), [make it listen](https://golang.org/pkg/net/http/#ListenAndServe) locally just for the Datadog Agent. {% tab title="Host" %} #### Host{% #host %} To configure this check for an Agent running on a host: ##### Connect the Agent{% #connect-the-agent %} 1. Edit the file `go_expvar.d/conf.yaml`, in the `conf.d/` folder at the root of your [Agent's configuration directory](https://docs.datadoghq.com/agent/guide/agent-configuration-files.md#agent-configuration-directory). See the [sample go_expvar.d/conf.yaml](https://github.com/DataDog/integrations-core/blob/master/go_expvar/datadog_checks/go_expvar/data/conf.yaml.example) for all available configuration options. **Note**: If you don't configure a `metrics` list, the Agent still collects memstat metrics. Use `metrics` to tell the Agent which expvar vars to collect. 1. [Restart the Agent](https://docs.datadoghq.com/agent/guide/agent-commands.md#start-stop-and-restart-the-agent). **Note**: The Go Expvar integration can potentially emit [custom metrics](https://docs.datadoghq.com/developers/metrics/custom_metrics.md), which may impact your [billing](https://docs.datadoghq.com/account_management/billing/custom_metrics.md). By default, there is a limit of 350 metrics. If you require additional metrics, contact [Datadog support](https://docs.datadoghq.com/help/). {% /tab %} {% tab title="Containerized" %} #### Containerized{% #containerized %} For containerized environments, see the [Autodiscovery Integration Templates](https://docs.datadoghq.com/agent/kubernetes/integrations.md) for guidance on applying the parameters below. | Parameter | Value | | -------------------- | ---------------------------------------- | | `` | `go_expvar` | | `` | blank or `{}` | | `` | `{"expvar_url": "http://%%host%%:8080"}` | {% /tab %} ### Validation{% #validation %} [Run the Agent's status subcommand](https://docs.datadoghq.com/agent/guide/agent-commands.md#agent-status-and-information) and look for `go_expvar` under the Checks section. ## Data Collected{% #data-collected %} ### Metrics{% #metrics %} | | | | | **go\_expvar.memstats.alloc**(gauge) | Bytes allocated and not yet freed*Shown as byte* | | **go\_expvar.memstats.frees**(gauge) | Number of frees*Shown as operation* | | **go\_expvar.memstats.heap\_alloc**(gauge) | Bytes allocated and not yet freed*Shown as byte* | | **go\_expvar.memstats.heap\_idle**(gauge) | Bytes in idle spans*Shown as byte* | | **go\_expvar.memstats.heap\_inuse**(gauge) | Bytes in non-idle spans*Shown as byte* | | **go\_expvar.memstats.heap\_objects**(gauge) | Total number of allocated objects*Shown as item* | | **go\_expvar.memstats.heap\_released**(gauge) | Bytes released to the OS*Shown as byte* | | **go\_expvar.memstats.heap\_sys**(gauge) | Bytes obtained from system*Shown as byte* | | **go\_expvar.memstats.lookups**(gauge) | Number of pointer lookups*Shown as operation* | | **go\_expvar.memstats.mallocs**(gauge) | Number of mallocs*Shown as operation* | | **go\_expvar.memstats.num\_gc**(gauge) | Number of garbage collections*Shown as garbage collection* | | **go\_expvar.memstats.pause\_ns.95percentile**(gauge) | 95th percentile of recent GC pause durations*Shown as nanosecond* | | **go\_expvar.memstats.pause\_ns.avg**(gauge) | Average of recent GC pause durations*Shown as nanosecond* | | **go\_expvar.memstats.pause\_ns.count**(rate) | Number of submitted GC pause durations*Shown as sample* | | **go\_expvar.memstats.pause\_ns.max**(gauge) | Max GC pause duration*Shown as nanosecond* | | **go\_expvar.memstats.pause\_ns.median**(gauge) | Median GC pause duration*Shown as nanosecond* | | **go\_expvar.memstats.pause\_total\_ns**(gauge) | Total GC pause duration over lifetime of process*Shown as nanosecond* | | **go\_expvar.memstats.total\_alloc**(gauge) | Bytes allocated (even if freed)*Shown as byte* | | **go\_expvar.memstats.total\_alloc.count**(count) | Bytes allocated (even if freed) as monotonic count*Shown as byte* | ### Events{% #events %} The Go-Expvar check does not include any events. ### Service Checks{% #service-checks %} The Go-Expvar check does not include any service checks. ## Troubleshooting{% #troubleshooting %} Need help? Contact [Datadog support](https://docs.datadoghq.com/help/). ## Further Reading{% #further-reading %} - [Instrument your Go apps with Expvar and Datadog](https://www.datadoghq.com/blog/instrument-go-apps-expvar-datadog)